- Created by Barbara Jones, last modified on Mar 13, 2020
H5O_GET_INFO3
Retrieves the metadata for an object specified by an identifier
Procedure:
H5O_GET_INFO3 (loc_id, oinfo, fields)
Signature:
herr_t H5Oget_info3 ( hid_t loc_id, H5O_info2_t *oinfo, unsigned fields )
SUBROUTINE h5oget_info_f(object_id, object_info, hdferr, fields)
USE, INTRINSIC :: ISO_C_BINDING
IMPLICIT NONE
INTEGER(HID_T) , INTENT(IN) :: object_id
TYPE(h5o_info_t), INTENT(OUT), TARGET :: object_info
INTEGER , INTENT(OUT) :: hdferr
INTEGER , INTENT(IN), OPTIONAL :: fields
Related Fortran2003 Derived Type: h5o_info_t
TYPE, BIND(C) :: h5o_info_t
INTEGER(C_LONG) :: fileno ! File number that object is located in
TYPE(H5O_TOKEN_T_F) :: token ! Token for object in file
INTEGER(C_INT) :: type ! Basic object type (group, dataset, etc.)
INTEGER :: rc ! Reference count of object
INTEGER, DIMENSION(8) :: atime ! Access time ! -- NOTE --
INTEGER, DIMENSION(8) :: mtime ! Modification time ! Returns an integer array
INTEGER, DIMENSION(8) :: ctime ! Change time ! as specified in the Fortran
INTEGER, DIMENSION(8) :: btime ! Birth time ! intrinsic DATE_AND_TIME(VALUES)
INTEGER(hsize_t) :: num_attrs ! # of attributes attached to object
END TYPE h5o_info_t
Parameters:
hid_t loc_id | IN: Identifier for object of type specified by H5O_type_t; may be a file, group, dataset, named datatype or attribute identifier |
H5O_info2_t * oinfo | OUT: Buffer in which to return object information |
unsigned int
fields
| IN: Flags specifying the fields to include in oinfo |
Description:
H5O_GET_INFO3 specifies an object by its identifier, loc_id , and retrieves the metadata describing that object in oinfo , an H5O_info2_t struct.
The H5O_info2_t struct is defined (in H5Opublic.h) as follows :
/* Data model information struct for objects */
/* (For H5Oget_info / H5Oget_info_by_name / H5Oget_info_by_idx version 3) */
typedef struct H5O_info2_t {
unsigned long fileno; /* File number that object is located in */
H5O_token_t token; /* Token representing the object */
H5O_type_t type; /* Basic object type (group, dataset, etc.) */
unsigned rc; /* Reference count of object */
time_t atime; /* Access time */
time_t mtime; /* Modification time */
time_t ctime; /* Change time */
time_t btime; /* Birth time */
hsize_t num_attrs; /* # of attributes attached to object */
} H5O_info2_t;
Note the following about H50_info2_t:
- Of the four time fields (
atime,mtime,ctime, andbtime) onlyctimehas been implemented. - The
atimevalue is the last time the object was read or written. - The
mtimevalue is the last time the raw data in the object was changed. - The
ctimevalue is the last time the metadata for the object was changed. - The
btimevalue is the time the object was created.
H5O_token_t is defined in H5public.h as follows:
/* Type for object tokens */
/* (Hoisted here, since it's used by both the H5Lpublic.h and H5Opublic.h headers) */
typedef struct H5O_token_t {
uint8_t __data[H5O_MAX_TOKEN_SIZE];
} H5O_token_t;
The H5O_type_t enum indicates the object type and is defined (in H5Opublic.h) as follows:
/* Types of objects in file */
typedef enum H5O_type_t {
H5O_TYPE_UNKNOWN = -1, /* Unknown object type */
H5O_TYPE_GROUP, /* Object is a group */
H5O_TYPE_DATASET, /* Object is a dataset */
H5O_TYPE_NAMED_DATATYPE, /* Object is a named data type */
H5O_TYPE_MAP, /* Object is a map */
H5O_TYPE_NTYPES /* Number of different object types (must be last!) */
} H5O_type_t;
Note that object_id refers only to the types specified by H5O_type_t.
The fields parameter contains flags to determine which fields will be filled in in the H5O_info2_t struct returned in oinfo. These flags are defined in the H5Opublic.h file:
| Flag | Purpose |
|---|---|
| H5O_INFO_BASIC | Fill in the fileno, addr, type, and rc fields |
| H5O_INFO_TIME | Fill in the atime, mtime, ctime, and btime fields |
| H5O_INFO_NUM_ATTRS | Fill in the num_attrs field |
| H5O_INFO_HDR | Fill in the hdr field |
| H5O_INFO_META_SIZE | Fill in the meta_size field |
| H5O_INFO_ALL | H5O_INFO_BASIC | H5O_INFO_TIME | H5O_INFO_NUM_ATTRS | H5O_INFO_HDR | H5O_INFO_META_SIZE |
Note:
If you are iterating through a lot of different objects to retrieve information via the H5O_GET_INFO family of routines, you may see memory building up. This can be due to memory allocation for metadata such as object headers and messages when the iterated objects are put into the metadata cache.
If the memory buildup is not desirable, you can configure a smaller cache via H5F_SET_MDC_CONFIG or set the file access property list via H5P_SET_MDC_CONFIG. A smaller sized cache will force metadata entries to be evicted from the cache, thus freeing the memory associated with the entries.
Returns:
Returns a non-negative value if successful; otherwise returns a negative value.
Example:
/*
* Find string attribute by iterating through all attributes
*/
ret = H5Oget_info3(dataset, &oinfo, H5O_INFO_NUM_ATTRS);
for(i = 0; i < (unsigned)oinfo.num_attrs; i++) {
attr = H5Aopen_by_idx(dataset, ".", H5_INDEX_CRT_ORDER, H5_ITER_INC, (hsize_t)i, H5P_DEFAULT, H5P_DEFAULT);
atype = H5Aget_type(attr);
type_class = H5Tget_class(atype);
if (type_class == H5T_STRING) {
atype_mem = H5Tget_native_type(atype, H5T_DIR_ASCEND);
ret = H5Aread(attr, atype_mem, string_out);
printf("Found string attribute; its index is %d , value = %s \n", i, string_out);
ret = H5Tclose(atype_mem);
}
ret = H5Aclose(attr);
ret = H5Tclose(atype);
}
! Check h5oget_info
CALL h5oget_info_f(grp, oinfo, error)
CALL check("h5oget_info_f", error, total_error)
IF(oinfo%rc.NE.1)THEN
CALL check("h5oget_info_f", -1, total_error)
ENDIF
IF(oinfo%type.NE.H5O_TYPE_GROUP_F)THEN
CALL check("h5oget_info_f", -1, total_error)
ENDIF
History:
| Release | Change |
|---|---|
| 1.12.0 | Function was introduced in this release. |
--- Last Modified: March 13, 2020 | 11:06 AM